Dinosaur mysteries with Riley Black

How do we know what we know about dinosaurs? Riley Black takes us back to the Mesozoic Era and explains how paleontologists piece together the lives of dinosaurs from often fragmentary clues. To watch this episode on video, find us on Netflix! Guest: Riley Black, science writer, amateur paleontologist, and consultant for the Jurassic World franchise. For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠And please email us! ⁠⁠⁠[email protected]⁠⁠⁠We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠⁠Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

• 0:00Speaker 00

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• 0:38Speaker 01

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• 1:09Speaker 02

  How do we know what we know about dinosaurs? I think about this whenever I'm in a natural history museum because you have these bones that are tens or even hundreds of millions of years old. They come from a version of our planet that looks pretty different from the Earth that we walk on today. So how do we take these fossils and spin them into the stories about dinosaurs that I love to read and watch?

• 1:39Speaker 03

  The dinosaurs are dead, yet in our imaginations, they are very much alive.

• 1:48Speaker 02

  My guest today, Riley Black, has written a lot about how to piece together an entire narrative from fossils. Riley writes about how we know what we know about dinosaurs.

• 2:16Speaker 02

  Riley, thank you for being on the show.

• 2:19Speaker 04

  Oh, my pleasure. I mean, you asked me to show up and bring my dinosaur stuff. How could I resist?

• 2:24Speaker 02

  For our listeners, Riley brought some dinosaur models and a cast of a dinosaur hand along. But Riley, can you tell me a little bit about who you are, please, and what you do?

• 2:35Speaker 04

  Sure. So I'm a professional science writer. I've written about a dozen books about prehistoric life in one form or another. And I'm also an amateur paleontologist. I go out in the field and actually find some fossils.

• 2:45Speaker 02

  I mean, if you are going out into the field, what is amateur about it?

• 2:49Speaker 04

  So there's a bit of a divide sometimes between the professional paleontology side and the many, many, many amateurs and volunteers out there looking for fossils. So I call myself an amateur because I'm not a curator or I'm not a professor. But I've been out in the field from places from Alaska to Mexico, a lot of work in the Four Corners, actually finding fossils that go to museums and are cataloged and studied there. So I do it for the love of it.

• 3:12Speaker 02

  But why dinosaurs?

• 3:14Speaker 04

  It's hard not to be into dinosaurs. I mean, so from what I was told, I went through a very short phase with trucks and then elephants, which I still love, and dinosaurs. So big and loud, I guess, is always what I've been kind of into. Went to the American Museum of Natural History when I was five.

• 3:30Speaker 02

  Heard of it.

• 3:31Speaker 04

  And when you are small, not as small as a mesozoic mammal, but still quite small, and seeing these big skeletons, it's hard not to be impressed. And what I love about them, and really any prehistoric life, is you look at their bones or their traces or what they leave behind, and there are all these questions of how did they move? What did they look like? What color were they? What did they sound like? What did they smell like? All of the stuff that we may or may not have answers to. So it was a chance to get to know this whole realm of science that's fueled by the questions where you're encouraged to use your imagination.

• 4:01Speaker 02

  I think this is a perfect transition into what I wanted to talk to you about today, which is how do we know the things that we know about dinosaurs? And so I thought maybe we could start sort of where the paleontologists first started, which is the skeletons that they left behind. So talk to me about how we sort of take a dinosaur skeleton, like a bunch of bones, and turn that into a story about reptiles running through the world.

• 4:27Speaker 04

  I mean, this is how paleontology as a science started. I think it's important to note that people have been finding fossils for thousands and thousands of years. We have like stone hand axes of fossils. In the indigenous cultures all over the planet, have encountered fossils of different kinds and understood that these were once living things. So like, we've had this long recognition that there was life before us. But it's the late 1700s. We have geology, which is starting as a science, and comparative anatomy, mostly in Western Europe. And you put those two things together, people find these weird bones, usually disarticulated, usually incomplete, but it's just big, big stuff, like a tooth from a reptile that's far larger than any crocodile or snake or anything that lives in that part of the world today. And they know this must be something. And they try and slot it into what they knew.

• 5:11Speaker 04

  So this is why the earliest representations of dinosaurs look like giant lizards or giant crocodiles. It's just like, what's a reptile that must have been 100 feet long? Then we get more complete skeletons. They're like, oh, okay, the body shape is entirely different, which is kind of funny. Brachiosaurus is a great example because we really only have the forelimbs and parts of the vertebra and some of the neck. And that's about it. So we're really basing it on other, more complete animals.

• 5:34Speaker 02

  Wait, wait, wait. This dinosaur?

• 5:36Speaker 04

  Yes.

• 5:37Speaker 02

  We have like these parts, the like, the front legs?

• 5:42Speaker 04

  Yes.

• 5:43Speaker 02

  Some of its neck?

• 5:44Speaker 04

  Mm-hmm.

• 5:45Speaker 02

  And what else?

• 5:46Speaker 04

  A few bits of its backbone along the spine, a couple limb elements, and that's it. There's some that I know are undescribed. There might be skull pieces.

• 5:54Speaker 02

  How do we, how do we make something like this from some forelimbs, some vertebra, some other bones, and a dream?

• 6:04Speaker 04

  Yeah, how we get to something like that surfer Brachiosaurus here.

• 6:07Speaker 02

  So you're, you're showing me right now a model you have of a beautiful, long-necked dinosaur with a long, curving tail, four lovely, long legs, red and green coloring.

• 6:18Speaker 04

  For something like Brachiosaurus, where we don't have the whole skeleton, even now, we look to their closest relatives. There's a related animal called Giraffatitan that's found in...

• 6:28Speaker 02

  Giraffatitan?

• 6:30Speaker 04

  Yes.

• 6:30Speaker 02

  Sorry, so like?

• 6:31Speaker 04

  Giant giraffe.

• 6:32Speaker 02

  Big giraffe.

• 6:33Speaker 04

  Yeah, we have the arm lizard, and we have the giant giraffe. Giant giraffe is more complete. And we can, they're close enough that, you know, we know that they must have had similar bones, like this is some, like, we know they're vertebrates, right? Based upon the bones that we find. So when you have a vertebrate, they must also have a circulatory system and a nervous system and skin. We can, even if we don't have the exact fossil, we can start filling in those pieces as a hypothesis. So anytime you see a complete dinosaur, unless it's really, literally that specimen or that cast that someone's made a one-to-one of, it's hypothesis. Anyone's vision of a dinosaur, like, I can say T-Rex. And the T-Rex I see in my head, it's going to be different from what you see in your head. And this is what I love about it, is that we're taking sort of this bare scaffolding and based upon what we know and what we see from experience, filling in like what might

• 7:18Speaker 04

  have been there.

• 7:19Speaker 02

  What are some of the most interesting or maybe even counterintuitive ways that we have been able to say, no, I'm pretty sure this looked this way, just, just by looking at the, the bones alone?

• 7:31Speaker 04

  So the bones alone, usually we need a complete skeleton or a fairly complete skeleton. It's how, but this little T-Rex hand that I brought in is a really good example. And this is an animal that would have been more than 30 feet long. And you can hold its hand in your hand. It would have been an arm about as long as yours.

• 7:48Speaker 02

  So I'm looking at, just to be clear, sort of what looks like two fingers of a T-Rex hand that have very pointy claws on the end of them.

• 7:59Speaker 04

  And you actually have a little bit of a third finger there. So there's a little splint bone that's underneath the larger fingers. And that third one, that splint, is the remainder of the third finger. We always make fun of T-Rex for having tiny, tiny hands, right? Well, they used to have three fingers and their ancestors lost them.

• 8:14Speaker 02

  Okay, so this tiny little bone, this like, this bone that's actually the size of my pinky is like an ancestral third finger, like a tailbone of a, of a third finger that they have?

• 8:25Speaker 04

  Right.

• 8:26Speaker 02

  Interesting.

• 8:26Speaker 04

  Which was lost. And we didn't know that. So when the first Tyrannosaurus rex was being reconstructed here in New York City, we used to think it was related to other carnivorous dinosaurs that we knew about. But there was no arm. You know, we had the big old skull, we had the backbone, ribs, all this stuff, no arms. The arms are tiny. Of course, they'd probably wash away and not get buried. It wasn't until someone actually found a T-Rex arm with the hand at the end of it. So early on, they thought, well, it's three fingers, like all the other carnivorous dinosaurs do. And then someone found a related form in Canada, in Alberta, that only had two. And we know that they were closer to T-Rex. It's like, okay, we're gonna, we have to change the model. And that's why T-Rex is two little fingers.

• 9:02Speaker 02

  Fascinating. Okay, so the, so finding bones, finding more bones to complete out a skeleton can really tell us, like, oh, we got this wrong, we got this wrong, et cetera. But you also had a, you had an article that you wrote that was also about tiny arms that was a little different that I, that I loved. Can you tell me a little bit about Alvarosaurus? Am I saying that right?

• 9:24Speaker 04

  Yes, yes, the Alvarosaurus. I'm glad to talk about them because nobody talks about Alvarosaurus. This is like the indie band that like, only does vinyl.

• 9:33Speaker 02

  Yeah, show me a picture of Alvarosaurus, please.

• 9:36Speaker 04

  This is a little critter called Mononychus.

• 9:38Speaker 02

  Oh, this is Mononychus?

• 9:39Speaker 04

  It belongs to a group called Alvarosaurus.

• 9:41Speaker 02

  So I'm looking at this very small, very cute creature that had, you know, has very long legs, it has a really long neck, and then it just has these rinky-dink little arms coming off of it that, that it's, it's holding together in a little...

• 9:58Speaker 04

  Oh, like a little, please, like a begging posture, like, can I go home an hour early, kinda, kinda pose? That's just one claw. That's what its name means, is one claw.

• 10:07Speaker 02

  So what is its one claw for?

• 10:10Speaker 04

  We don't know. We don't know because a skeleton can't really tell us exactly what it's for.

• 10:16Speaker 02

  Right.

• 10:17Speaker 04

  In that it can give us the range of motion and we can reconstruct the musculature and things like that. But it can't really tell us, like, what did it use that musculature for? How did it move those limbs? If we know it has a short range of motion, then to what purpose, what function?

• 10:32Speaker 02

  Are there ideas?

• 10:34Speaker 04

  Yes.

• 10:34Speaker 02

  Do people have theories? Okay, love a theory.

• 10:37Speaker 04

  So my favorite one is that these were dinosaur anteaters because they often have either no teeth or very, very, very small teeth. And this is something that we see happen with like a shift away from carnivorous foods and more towards like insects and plants and things like that. But we think that they were like anteater dinosaurs using those little claws to basically stick their chest to the ground and just kind of scratch away at ant and termite mounds, which we know were around at the time. We actually find dinosaur bones sometimes with termite damage to them.

• 11:03Speaker 02

  So theory one is they were anteaters, just like poking their fingers in there. What is the other, what are the other theories for what these tiny claws could be for?

• 11:16Speaker 04

  They might have been for grasping eggs. There was a species that was named a few months ago that they thought that they were just kind of clasping eggs to their chest. They're just kind of doing a little dip, picking up an egg and kind of skittering away with it.

• 11:29Speaker 02

  Okay.

• 11:30Speaker 04

  And that's really about it so far. We don't really like it. You look at that stubby arm, it's just kind of like, what? And there's not a whole lot else. We don't have a lot of equivalence for arms like these other than animals that, that dig into the ground somehow.

• 11:44Speaker 02

  Okay, so we have T-Rex claws, we have Alvorosaurus claws. Are there other sort of dinosaurs where we're just sort of like, well, we have a bunch of bones. What could this possibly be? What does it look like?

• 11:57Speaker 04

  So dinosaurs love their bizarre structures. Like the fashion through the Mesozoic was just something else. Like the ornamentation on these animals constantly, like your little triceratops friend, even though that's a very traditional, you know, three horn face look. There are lots of horned dinosaurs with all these different arrays of horns and spikes and hooks and everything else that help them differentiate each other. And that we have a fair handle on. But in terms of ornamentation, there are dinosaurs with like sails on their backs and we have no idea why.

• 12:26Speaker 02

  Sails?

• 12:27Speaker 04

  Yes, sailback dinosaurs. So there's one in particular called Oranosaurus. This is an herbivore. So everybody knows Spinosaurus that got its name for the spines on its back, right?

• 12:37Speaker 02

  We're doing indie dinosaurs here. We're not doing Spinosaurus.

• 12:41Speaker 04

  The it girl, like on the cover of Nat Geo, we're doing, again, the deep cuts. So this is an Oranosaurus. It is something related to Iguanodon, or the duck beat dinosaurs, and it has a sail on its back.

• 12:55Speaker 02

  Okay, so I'm looking at a dinosaur, it's very difficult to describe. So the middle part of it sort of looks like a regular dinosaur. And then on its back, it just has like a whole fan of bones coming out. So I see what you mean now about a sail. What, I feel like I know the answer and the answer is we don't know, but what is, what's the sail for?

• 13:21Speaker 04

  We don't know. Amazingly, there have been a few ideas. One of which, one of my favorite sort of discarded hypotheses, that we see these long neural spines, so these flat bones that come up off the backbone in things like bison or various mammals, and they usually hold a hump or the end of a ligament that goes from the back of the head to between the shoulders. Because a lot of these mammals have big, heavy heads, they need like an extra basically rubber band to help them keep their heads up. And we used to think that this was true for the dinosaurs as well, but then you'd have this basically mound-shaped dinosaur with legs. If you imagine like a little hill with legs kind of shuffling around, that's more or less what they would look like. But that was one of the ideas, that this is some sort of head support or something like that.

• 14:03Speaker 02

  Okay.

• 14:04Speaker 04

  What seems more likely is it's some kind of billboard. Basically, it's dinosaur advertising, that they're communicating to other members of their species, saying like, I'm bigger than you, or I'm an adult, or I'm a juvenile, or like different dinosaur sexes.

• 14:18Speaker 02

  Like a peacock tail almost, but on their, a permanent peacock tail on their back.

• 14:24Speaker 04

  Yes, always peacocking. And they're lucrative. Yeah, and with something that's that big and that elaborate, and it takes energy to grow, right? This is an investment this animal is making, bone is constantly remodeling itself. It must have had, formed some purpose in this animal's life. But unless we can see these dinosaurs interact, it's very difficult to tell what they were doing. Now, there's some ways that maybe we can get at it, if we can find some skin and find out what color that skin was, which is a thing we can do now, maybe we can start to get at it.

• 14:54Speaker 02

  Right.

• 14:54Speaker 04

  But again, it takes the luck of the fossil record to actually make such a find.

• 14:58Speaker 02

  Got it. So if you could find like skin from another part of its body and then skin from this sail, and the skin on the sail was like neon, and the skin on the rest of its body was like fairly gray, it would be relatively clear. And the neon sign said like, two for a dollar at Spinosaurus Land, you'd be like, oh, it's a billboard.

• 15:20Speaker 04

  Yeah, that vaporwave aesthetic going on the sail.

• 15:24Speaker 02

  Amazing. So what you've told us to this point is essentially that skeletons can't tell us everything we need to know. Bones are not the be all and end all. We still have a lot of questions, we have questions about the sails on dinosaurs like Oranosaurus or even Spinosaurus, or what Alvorosaurus use their claws for. What else can we look at to understand dinosaurs in more depth?

• 15:49Speaker 04

  Yes, so you're getting to one of my favorite kinds of fossils, and those are trace fossils.

• 15:53Speaker 02

  Trace fossils?

• 15:55Speaker 04

  Yes, so these are things that animals leave behind in the fossil record. So it's not the tooth of the bone or whatever itself, but it's the marks that animal made in life. So we're talking about things like tooth marks and tracks and fossil feces and all these other things that basically an animal leaves behind just through living.

• 16:16Speaker 04

  It's interaction, it's behavior. So like when you see a dinosaur trackway, it's not just footprints in the rock, that is moments in that animal's life and we can calculate like how tall it was, how fast it was moving, maybe the direction it was going in. Is there another animal nearby? Is it going in a certain direction like to get around an obstacle or to avoid something? So these are actually like moments of prehistoric time that we still have as fossils.

• 16:42Speaker 02

  More on that after the break.

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• 18:32Speaker 02

  What's your, like, what's one of your favorite? Already pulling out the phone to show me something?

• 18:37Speaker 04

  Well, now I get to brag a little. I get to talk about stuff that I have found out in the field.

• 18:42Speaker 02

  What's one of your favorite traces?

• 18:44Speaker 04

  One of my favorite traces, so what I'm, what I'm showing you on the phone is it kind of looks like multiple toes there. You can see one, two, three, four.

• 18:53Speaker 02

  Yes.

• 18:53Speaker 04

  And then there's a couple of small toes next to it. So it's basically the front foot and the back foot of a crocodile-like armadillo thing called an aetosaurus.

• 19:03Speaker 02

  Okay, aetosaurus. How do you know, just is it like, that's what matches up that footprint?

• 19:08Speaker 04

  Yeah, so you can look at the skeletons and you can look at what other animals are found in that formation and see how whose foot matches what print. It's rarely one to one. Unless an animal literally dies in its tracks, but sometimes this happen. It's hard to be 100% certain, but in this case, the hand and foot anatomy matched this armadillo-like crocodile relative that was nirbivore, that was living around when dinosaurs were really small. And just kind of, it looked like the ground was giving me a high five. It was like impossible to miss.

• 19:38Speaker 02

  And so how did you find this?

• 19:40Speaker 04

  Yeah, so I was out on expedition with the Natural History Museum of Utah, out in the eastern part of the state. So like outside Arches National Park, that kind of area, desert country, you're miles and miles from, from anybody. And the rocks are very, very ancient there. So we're talking about the end of, sort of the dawn of the dinosaurs, the Triassic, about 220 million years ago. You hop out of the truck, you have your water and everything that you need for the day, and you just go walking and looking for fossils. So I start picking around the rocks nearby. And you have to look at these walls of rock and kind of determine what layers you're going to look at, where, where you're going to go, like the angle of the sun that can matter in terms of what you're going to find. And I start picking along and I find these little invertebrate traces, basically little like beetle footprints.

• 20:24Speaker 04

  And it's like, okay, there are traces here. So I find those little beetle traces, I find a little plant fossil, and then there's a dinosaur track. I actually have a, brought one of the photos of that one as well. And this was like indisputable, that's what it was as soon as I saw.

• 20:39Speaker 02

  Oh, yeah. So I'm looking at what is, it looks like a footprint.

• 20:42Speaker 04

  Yeah, just looks like a little chicken track. It was about that, that size, really, just those three toes with the claws at the ends. And then I start taking my field notes and start, you know, looking for other stuff. And I see that footprint from the aetosaurus, as well as a whole bunch of other ones. Like now I'm, you know, just reliving this trip, basically having a happy little flashback here.

• 21:01Speaker 02

  But so you have these, you have these footprints. What, what can those footprints tell you?

• 21:08Speaker 04

  Yeah. So footprints can tell you an animal's moving speed. There's a relatively simple calculation that you can use between foot strides to tell how fast it was likely moving. Longer apart usually means it's moving quicker. It's really basic, like kind of like animal physics kind of stuff. One of my favorites, it's not this site, but it's at a place nearby where I found those tracks. It's a Jurassic Age site that has tracks that were likely made by an animal like Allosaurus. So think like a Jurassic T-Rex, just three fingers, a little bit smaller. And the stride lengths on one foot are different than the other. And what that means is that dinosaur's limping. So it got injured somehow. And we have an injured dinosaur trackway. And we don't entirely know what caused it, but it's just a great reminder of like, these animals

• 21:53Speaker 04

  dealt with the same kind of like injuries and bone breaks and everything that we see in animals now.

• 21:58Speaker 02

  They were, they were living lives. They were not sort of perfect specimens of dinosaur hood. They were, each one was an individual dinosaur with its own little trials and tribulations, I guess. Is there something that trace fossils have helped us? Are there ways that they've sort of changed our understanding of some of the skeletons that we've received? Or, or sort of upended things that we thought we understood about dinosaurs?

• 22:29Speaker 04

  Absolutely. So trace fossils are not just for dinosaurs. All sorts of prehistoric things, left traces, and including traces on dinosaur fossils. So there's a place in western Colorado called Mygatmore Dinosaur Quarry. It's like 150 million years old. This is like heyday of Allosaurus, Stegosaurus, Apatosaurus, like all those favorites. But everything there is in a jumble. So we don't get complete skeletons out of that site. It's this, basically this pond where things were disarticulating and falling apart and scavengers came by. There's so many bite marks on these fossils. You see like the ends of thigh bones. They're just raked with these teeth from all the feeding and stuff. And we can tell from where those bite marks are, sort of what were the favored parts of like a sauropod body. So if you have an Allosaurus coming to scavenge, where is it going to start?

• 23:14Speaker 04

  Some of it suggests that they were going in through the cloaca to get at the pelvis after they'd taken off like the other tail meat and stuff.

• 23:22Speaker 02

  So they were going in through, sorry to be crass, the butthole?

• 23:26Speaker 04

  Yes, they were. Yeah. Yeah. They would enjoy like basically, you know, the, there's a big tail muscle called the caudifemoralis that they'd take that stuff first. And when they're getting down on like the prime cuts, that's how they got into the rest of it.

• 23:38Speaker 02

  I'm such a child.

• 23:42Speaker 04

  So we have those bite marks on those bones, but we also have beetle damage. So a lot of museums use like dermestid beetles to clean their skeletons, right? You have a skeleton, you want it to be clean for display. You put it in with the beetles and then you take it out before the beetles start to burrow into it, because that's what they want to do. They want to.

• 23:56Speaker 02

  Sorry, I love that you're saying this just sort of like casually. And we all know, sorry, they use beetles to clean specimens. Okay, great.

• 24:04Speaker 04

  Yes.

• 24:04Speaker 02

  Fact I learned, but.

• 24:07Speaker 04

  Yes. So those beetles, normally to complete their life cycle, they want to burrow into that bone. So naturally that's what tends to occurs. And that's what we find on some of these dinosaur bones, that they were exposed now in the open long enough that those beetles were like basically eating their way through the bone, leaving trails in them, which tells us those bones were exposed like on the surface for a while. So this whole idea of we need quick burial to make a dinosaur fossil, probably not true. Some of these bones were on the surface for months, even years before they got buried, which makes sense. Because even though we have our pint-sized brachiosaurus in front of us, the real animal would have been about, you know, like 60 feet long and weigh upwards of 20 tons. Takes a lot of sediment to bury something like that. So by looking at what the insects were doing, the traces that they left,

• 24:51Speaker 04

  it's the same kind of stuff that forensic investigators use today to kind of determine how long a body has been exposed. We can do that with dinosaurs, thanks to traces.

• 24:59Speaker 02

  So if we return to sort of the, the questions you were laying out at the beginning about, say, like Alverosaurus, why does it have such tiny little finger claws? Could trace fossils potentially help us kind of answer the questions that are posed by these skeletons?

• 25:16Speaker 04

  Yes, because one of the things that we always want to know about dinosaurs, right, is what did they eat? And so often when it comes to the teeth and claws and other things, it comes down to a question of feeding and how are they acquiring that food and how are they processing it? So we think of our little Alverosaurus friends, a little friend like Monochychus. If they were, you know, sticking their chest against an ancient termite mound, which also like, ow, I hope they don't bite. This sure is a strategy to pick. And digging away with their arms, we might be able to find a prehistoric termite mound that has scratch marks in it. We actually have scratches made by dinosaurs in the fossil record from Utah in a different part of the state than I was prospecting in. There is a mammal burrow that has claw prints from a Velociraptor-like dinosaur, basically digging in.

• 26:01Speaker 04

  That this dinosaur is trying to dig into the burrow to pull the mammals out. So we could find something like that with Alverosaurus, these claw scratches on the insect mounds, and that would give us some clues. More likely, we're going to get the answer through fossil poop, coprolites. So coprolites, that's a kind of trace fossil. It's basically what an animal is eating. It's, it's the remainder of the gut contents. Sometimes we get gut contents. Sometimes we get something called a cololite, which is basically when it's in the intestine but hasn't exited yet. Coprolite is just fossil poop. Usually contains, if there were scales or exoskeletons or anything like that, it would be in there. So if Alverosaurus were eating these little insects, we should be able to find a coprolite from them. There'll be more coprolite fossils than skeletal fossils, because they'd be making them all the time, basically back in the Cretaceous.

• 26:46Speaker 04

  And these should be full of little ants or termites or some of that. Or maybe we'll look into them and find eggshell or little mammal bones. Or who knows what, but that would be the test of the actual animal's behavior. We can look at their skeleton and say like, maybe they did this. But traces, like basically to have the remainder of what they actually ate.

• 27:05Speaker 02

  How would you know it was an Alverosaurus coprolite?

• 27:08Speaker 04

  That's a great question, because you wouldn't really be 100% sure, except if it were exceptionally rare. So most of the time we find coprolites just by themselves. They're just individual fossils. And we can say, okay, the body size matches, or based upon what we've collected for other animals, it seems like it came from a similar sort of animal. If we found it as a cololite or found it associated with a skeleton, then you could say like, okay, these are close together. You know, like there's some kind of association between them. So it's probably that, might be able to look at the geochemistry. But here's the thing, right? Like, it goes back to what you were saying at the beginning. For anything that we find in the fossil record, it's like, find one fossil, here's a dozen questions.

• 27:50Speaker 02

  And what, I guess, what keeps you interested in sort of trying to piece everything together?

• 27:58Speaker 04

  There's always something more to learn. There's always something that I didn't know. Nature is so surprising, even familiar animals. Even the most basic questions about dinosaurs, we don't necessarily have answers for yet. But in my lifetime, the amount of things that we've learned, that I was told even as a kid, we were never, ever going to know. For example, dinosaur color used to be, you know what? Do whatever colors you want. Nobody knows what color dinosaurs were. You know, make that neon pink, you know, T. rex or, you know, stegosaurus with, you know, bright yellow plates or what have you. Now we're starting to find out what colors they actually were by comparisons to modern birds and looking at, you know, skin and feathers and the microscopic nature of it that creates structural color. So, you know, in a way, like, it didn't kill the magic, it just made it more interesting.

• 28:42Speaker 04

  Like, okay, we got some color. Now, what other colors were there? What color patterns were there? Did they vary between different sexes or populations or species? So, all of this curiosity, it's incremental and cumulative, and it changes our perception of what the ancient world was like. I love the fact that the dinosaurs that I grew up with, especially seeing older documentaries and books and out of date museum displays, are now fundamentally different. It's the same species, sometimes the same skeletons, but they're rearranged, they're brought to life in a different way. And it feels like something that everybody can participate in. And I love that paleontology can be welcoming in that way, that it's something, if you can put boots on and go look for fossils, or even just like volunteering in a museum, poking through drawers, you can change the way people see ancient life.

• 29:28Speaker 02

  Love that. Riley, thank you so much for coming on, talking to us about dinosaurs. If people want to read your books, which one would you recommend that they start with?

• 29:39Speaker 04

  I would recommend The Last Days of the Dinosaurs.

• 29:42Speaker 02

  Okay.

• 29:42Speaker 04

  It is the first narrative book that I wrote. So, this is like if you were there 66 million years ago, you're standing in ancient Montana from the day before the asteroid hits, through the first hour, the first day, the first week, through the first million years, as you see life change. It's basically the making of the world as we know it now, with the reason why we're here. So, if you really want to get a feel for not only what it's like to be there in the Mesozoic, but sort of the way that I think a paleontologist sees the world, the way that I see the world when I'm out in the rocks, when I'm looking for these animals, the kind of visual, mental landscape that you kind of create from what you know, I think that's the best place to start.

• 30:22Speaker 02

  All right. Riley Black, they are a science writer, amateur paleontologist, and a wonderful guest. So, thank you so much.

• 30:32Speaker 04

  Oh, it's been a joy.

• 30:40Speaker 02

  If you want to know more about Riley's books, we will link to their website in the description for this episode. This episode was produced by Valerie Shankman and me, Bert Pinkerton. It was edited by Joanna Solotaroff. Our video editor is Alex Coles. Our animator is Karim Correa. Our fact checker is Melissa Hirsch. Our studio engineers are Devon Howard and Joe Nebress. Mixing and sound design by Christian Ayala, music from Noam Hassanfeld, and Meredith Hodnott runs the show. Special thanks, as always, to Brian Resnick for co-creating the show with me and Noam. And if you want to see the video version of this episode, you can find us on Netflix. If you have thoughts about the show, we would love to hear from you.

• 31:25Speaker 02

  Please email us at [email protected]. Or if you'd like to support the show, join Vox, become a member. Just go to vox.com/members. And if you signed up because of us, please let us know, and thank you. Unexplainable is part of the Vox Media Podcast Network, and we'll be back soon.

• 31:52Speaker 06

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